Knife blade microswitch

ABSTRACT

A linear-to-pivotal motion converting mechanism including a pair of blades pivotally secured at the ends in spaced relation in the form of a variable-area quadrilateral, hubs mounting the blades for pivotal movement about points displaced from the centers of the respective blades and an actuator for moving the hubs apart transversely thereby causing the blades to pivot about the hubs is disclosed. An electrical switch utilizing the mechanical movement is also disclosed. The switch is suitable for miniaturization as a microswitch and provides a knife switch wiping action with electrical contacts.

United States Patent inventor Hal R. Linderfelt 1594 8.15. SkylineDrive, Santa Ana, Calif. 92705 Appl. No. 882,513

Filed Dec. 5, 1969 Patented Nov. 2, 1971 KNIFE BLADE MICROSWITCH 39Claims, 10 Drawing Figs.

Int. Cl H0lh 3/00 Field of Search 74/89, 99;

ZOO/6,17,64,53,l53.8,153.12, 156,159; 335/189, 190

[56] References Cited UNITED STATES PATENTS 2,680,970 6/1954 Durkee3,390,584 7/1968 Carroll Primary Examiner-Milton O. Hirshfield AssistantExaminer-Mark O. Budd Attorney-Fowler, Knobbe & Martens ABSTRACT: Alinear-to-pivotal motion converting mechanism including a pair of bladespivotally secured at the ends in spaced relation in the form of avariable-area quadrilateral, hubs mounting the blades for pivotalmovement about points displaced from the centers of the respectiveblades and an actuator for moving the hubs apart transversely therebycausing the blades to pivot about the hubs is disclosed. An electricalswitch utilizing the mechanical movement is also disclosed. The switchis suitable for miniaturization as a microswitch and provides a knifeswitch wiping action with electrical contacts.

PAIENTEDuuvz- [9n 3, 17,570

' sum 10F a INVENTOR.

Fan 4 5/ (M0565 MAFTEAG KNIFE BLADE MICROSWITCH This invention relatesto electrical jswitches in general and more specifically to miniatureelectrical switches commonly referred to as microswitches. Morespecifically, this invention relates to a microswitch using a novell'inear-to-pivotal motion converting mechanism in which electricalcontact is completed by knife switch wiping action.

Microswitches of several designs are commonly used throughout industry.Most of these microswitches which are standard in the industry sufferfrom several deficiencies. For example, such switches often fail tomaintain open and/or closed contacts due to the inherent susceptibilityof commonly used reed-type contacts to shock or. vibration. Motionsuddenly imparted to the switch housing causes the reed to flutter inthe housing thereby making or breaking electrical contact independent ofany actuation. This sensitivity of the microswitch to vibration resultsfrom an unbalanced or asymmetrical configuration with respect to thepivot points of the movable elements, the reed for example, in theswitch. This difiiculty is overcome in the present invention in whichone feature is the arrangement of the masses of the linkage elements inperfect balance about any and all axes through the rotational center ofthe mechanism. Acceleration forces due to shock, vibration or change ofvelocity, therefore, cannot exert a force to cause motion in the switchmechanism or the electrical contacts. An important feature of theinvention, then, is a microswitch design which is substantiallyunaffected by external acceleration.

In addition to being sensitive to shock or vibration, contemporarymicroswitches are frequently subject to failure due to contamination onthe contact points. These contact points are quitesmall, particularly onthe subminiature switches, and the point contact pressure is low.Microscopic particles of nonconductive material, such as lint, settlingbetween the points effectively prevent electrical contactfand can beresponsible for serious failures of entire systems. Such contaminationis particularly hazardous where the switch is used in a vibratingenvironment which can mobilize foreign particles within the switchhousing.

When microswitches are used in a cryogenic environment, icing of thecontact points is a rather common failure. Electrically conductive wire,such as copper, is an excellent conductor of heat and the switchcontacts are likely to be the coldest elements in the switch housing.Consequently, any moisture in the gas in the housing will condense onthe contacts to form a thin layer of ice. Electrical contact is notentirely prevented, but since the ice is a very poor electricalconductor, icing of the contacts may result in serious failures.

The foregoing difficulties are overcome in the present invention, onefeature of which is the utilization of the wiping action of a knifeblade type switch. The surface area of the switch contacts, in thepresent invention, is several times as great as in ordinary microswitchcontact points. This reduces contact resistance and increases contactreliability. The contact wiping action is self-cleaning, as opposed tothe ordinary microswitch "kissing" contact. Indeed, the knife bladeswitch has been recognized as one of the most reliable of all electricalmechanisms.

The foregoing difficulties are also obviated to a large degree by thepresent invention in which one feature is the provision of an actuatingmechanism which permits encapsulation of the entire switch. Actuationmay be accomplished through an airtight bellows, for example. Thisallows evacuation of the switch and, if desired, backfilling withdry gasor an inert gas, such as helium for cryogenic applications. This alsoprevents entry of foreign particles into the switch housing. Switches soencapsulated and actuated are, of course, suitable for use in virtuallyany environment, such as under water, in chemical operation, etc.

Microswitches generally lack sufiicient overtravel of theswitch-actuating plunger. This makes proper adjustment of mechanicalactuating means very difficult and is often impossible to accommodatefor dimensional variations caused by changes in temperature or bychanges in load deflection. Buildup of foreign substances on theactuator member is also a frequent problem. These problems are usuallysolved by interposing a spring deflection device as a safeguard betweenthe switch and the switch actuator. In certain instances, the spaceoccupied by such spring deflection devices and the weight contributionof such devices may pose problems in addition to those previously noted.One of the features and advantages of the present switch design is thatovertravel two or more orders of magnitude greater than is possible withcontemporary microswitches is easily provided. Any required degree ofovertravel is simply achieved without significant modification of theoverall design. Pretravel, in addition, may be virtually eliminated orany desired level of pretravel provided.

Conventional contemporary microswitches are available off the shelf inthe single pole, double throw configuration. This switch can, of course,be used as a single pole, single throw switch but when double throw, ortriple or quadruple pole switches are required, as is frequently thecase, it is necessary to connect two or more switches together side toside and to actuate them with a special actuator. Aside from theincreased weight and bulk, which may present problems in certainenvironments, simultaneous actuation is not always achieved. Thesedisadvantages are overcome by one feature of this invention in which amicroswitch can be easily and economically produced as a standardcomponent which is suitable for use as a single, double, triple, orquadruple pole, single or double throw switch.

By combining the several advantageous features of this invention, asimple, reliable, microswitch which is immune to shock or vibrationalforces, and which employs an efficient knife blade contact wiping actionwith large overtravel capability and with multiple-circuit provision isavailable. The switch is readily adaptable to being hermetically sealedand, with state of the art adaptations, can be easily converted to apressure-sensing, temperature-sensing, or other environmentalcharacteristic sensing switch or to a switching relay.

Another feature of the invention is that the switch can be manufacturedfrom readily available, inexpensive materials to easily obtainabletolerances and without the necessity for threaded holes, screws, etc.The simplicity of the mechanism and assembly will, therefore, permit lowunit production costs with minimum tooling costs. The disadvantages ofclose tolerance requirements and special alloy and material requirementsoften encountered in the manufacture of microswitches of the prior artare thereby avoided.

The advantages of this invention are obtained through the use of a novelmechanical movement which, in itself, constitutes one of the importantfeatures of the invention. This movement comprises a pair of elongatemembers which are pivotally secured near the ends thereof in relativelyspaced relation, so as to form a quadrilateral which is variable in areaand in width, (the width being measured perpendicularly from therespective members). The elongate members, in the form of rods, blades,etc., are substantially rigid and are individually mounted for pivotalmovement about respective pivot points and reciprocal movementtransversely of the longitudinal axes of the members. One or both pivotpoints are displaced from the centers of the respective members.Preferably, the pivot points of both members are displaced from thecenter. but are asymmetrically located. Actuating means are provided forreciprocally moving the mounting means apart or together, transverselywith respect to the members, the coaction of the end interconnection,pivotal mounting and relative transverse motion causing the members,referred to for convenience as blades, to pivot about the mountingmeans. A variety of actuating means may be provided.

The switch of this invention includes the aforesaid mechanical movementin a switch housing which also comprises one or more electrical contactsets positioned so as to be opened and/or closed by the reversiblepivotal movement of .the blades when actuated or deactuated. Animportant feature of the invention is the provision of a plurality ofelectrical contacts in the switch actuatable by the same pivotalmovement of the blades.

Other novel and important features and advantages of the invention willbecome apparent from the specification which follows and from thedrawings to which reference is now made.

FIG. 1 is a perspective view of one embodiment of the switch of thisinvention, showing a bellows actuator and being suitable for hermeticsealing.

FIG. 2 is a cross-sectional view of a variation of the switch of FIG. Icorresponding to a view taken substantially along lines 2-2 lookingdownwardly in the direction of the arrows as shown in FIG. I, showingthe mechanical movement of the switch in a first, deactuated, position.I

FIG. 3 is a cross-sectional view corresponding to a view takensubstantially along lines 3-3 of FIG. 1 looking sideways in thedirection of the arrows, showing one embodiment of the mechanicalmechanism and the switch in the first, deactuated position, as in FIG.2.

FIG. 4 is a cross-sectional view corresponding to a view takensubstantially along lines 2-2 of FIG. 1 looking downwardly in thedirection of the arrows, as in FIG. 2, but showing the mechanicalmovement and switch of this invention in the second, actuated, position.

FIG. 5 is a side cross-sectional view corresponding to a view takensubstantially along lines 33, as shown in FIG. 1, showing the mechanicalmovement and switch of this invention in the second, actuated, positionas in FIG. 4.

FIGS. 6 and 7 are schematic representations showing alternativeactuating mechanisms.

FIGS. 8, 9 and I0 illustrate another embodiment of the invention inminiature form; FIG. 8 being a side view of the switch shown in crosssection; FIG. 9 being a cross-sectional view taken along lines 9-9 ofFIG. 8, and FIG. 10 being a partial cross-sectional view showing theswitch operating structure taken along lines 10-10 of FIG. 8.

The mechanical construction and operation of the movement and switch ofthis invention will be explained for purposes of reference hereinafter.It is to be understood that the embodiments of the invention describedand illustrated exemplify the mechanical movement and an application ofthe mechanical movement to a particularswitch geometry, and that theillustrations are not limitive of the scope of the invention.

The switch I0 of this invention, as illustrated in FIG. 1, ineludes ahousing which, as will be explained in greater detail hereinafter, issuitable for being hermetically sealed.

As best illustrated in FIGS. 2 and 3, the housing, in the embodimentillustrated, comprises a top plate 12, a bottom plate 14, and spacersections 16, I8, and 22 forming the sidewalls of the housing. Theembodiment is an illustration of a working model of the inventionwherein the spacers and top and bottom plates of the housing wereseparate elements. It is contemplated, however, that in production thehousing will be made of two units adapted to be joined to form a closedhousing. In the illustration the housing is substantially square but, aswill be explained hereinafter, 'the housing may advantageously berectangular rather than square, or may be in a variety ofconfigurations. As in electrical switches generally, the housing ispreferably made of an insulating material such as a phenolic resin,nylon, ceramic material, etc. The switch of this invention may, ofcourse, be constructed according to the design criteria discussed hereinusing conventional mechanical and electrical engineering principles inthe production of the switch and in the adaptation of the switch toparticular uses. f

In the illustrated embodiment of the invention one of the spacers, 22,is provided with an aperture, shown at 24, and a grommet 26 throughwhich a multiconductor cable 28 extends.

The individual conductors 30 and 32 for example, are connected to theelectrical contacts in the housing as illustrated, for example, at 34and 36, forming one set of contacts, and at 38 and 40 forming a secondset of contacts. Additional pairs of contacts shown at 42 and 44 and at46 and 48 are also conveniently provided. One. two, three or four setsof contacts are easily provided as shown in the illustration. Each setof contacts may include a single contact or two, three or more contactsdepending upon the switching requirements. When the switch of thisinvention is miniaturized to form a microswitch, the number of contactswould be limited by the space available in the housing, but eight or 12contacts are easily provided.

The contacts are in the form of leaf springs and are convenientlycarried on the supports 50, 52, S4 and 56 as illustrated in FIGS. 2 and3. These supports may be made of any conventional insulating materialand are conveniently formed integrally with the housing. The contactsmay be secured to the supports and the conductors 30 and 32, forexample, to the contacts by screws, as illustrated, or preferably bysoldering, riveting, or the use of simplified frictional fasteners. Whenthe switch is miniaturized, contact connections can easily be made usingprinted-circuit techniques.

Electrical contact is completed and broken by the reversible pivotalmovement of the mechanism of this invention, the operating elements ofwhich comprise members 58 and 60, which are referred to as blades in theswitch of the invention. While several alternative modes of constructionand electrical circuit making and breaking are possible, in a preferredembodiment of the invention the blades 58 and 60 are composed, in partat least, of an insulating material such as phenolic resin or phenolicresin bonded glass or other fabric, ceramic material, or any otherinsulating material of suitable strength.

The blades 58 and 60 carry one or more conductive leaves, such as theleaf 62 which is illustrated in FIG. 2 as completing a circuit betweencontacts 34 and 36. The conductive leaf 64 is adapted to resilientlydisplace one or more contacts, 38 and 40 for example, by wiping actionto complete the circuit therebetween. The leaf 66 is adapted to make theelectrical circuit between the contacts 42 and 44 and the conductiveleaf 68 is adapted to complete the circuit between the contacts 46 and48 in the same manner, as shown in FIGS. 2-5.

The conductive leaves, in this embodiment of the invention. are bondedby adhesive, friction fit or otherwise to the blades 58 and 60,respectively, and they are composed of a conductive material. Accordingto good electrical engineering practice the conductive material may besilver, copper, silverplated copper, brass, or other conductivematerial. In certain instances it may be desirable to use a hard metalas the leaf, such as tungsten or tungsten alloys, where contactresistance is less important than wear resistance.

One or more of the conductive leaves may be electrically interconnectedby any desired circuitry. Printed circuit techniques are preferred inthe microswitch embodiment of the invention. Electrical interconnectionbetween leaves on the respective switch blades may be accomplishedthrough the use of flexible conductors, springs, or through theinterconnection between the switch blades. The number of conductiveleaves, the configuration and placement of the conductive leaves, andthe interconnection therebetween. is subject to great variabilitydepending upon the switching requirements. The embodiment illustrated issuitable for producing the switches on a mass production scale forgeneral use. For particular applicability, custom design of theswitching arrangement and interconnecting circuitry may be easilyaccomplished. The number and configuration of contacts, leaves, etc. andinterconnection is limited only by the space available in the particularhousing. Thus, extreme miniaturization may limit the number of contactsto eight, as shown in the illustration, while custom switching of alarge number of circuits may be accomplished using larger switchingcomponents.

Similarly, the current capacity of the circuit switched is limited bythe size of the contacting surfaces; thus the switching of extremelyheavy electrical currents will require larger switching components. Allthese considerations are, of course, well within the skill of the art.

In the illustrated embodiment, the switching is accomplished byconductors carried on the switch blades. It will be understood, however,that the switch blades may indirectly actuate switching. That is to saythat the mechanical motion available through the movement of thisinvention may be used as an actuating motion for making and breakingelectrical switches which are electrically independent of the switchblades. The movement of this invention, then, may be used merely toimpart actuating motion to an otherwise separate switching system.Indeed, the mechanical movement of this invention has utility completelydistinct from the switching application in which it is embodied in theillustrations of FIGS. l-5.

The blades 58 and 60 are pivotally secured proximate the ends thereof inrelatively spaced relation, as illustrated. The blades may be securedproximate the ends thereof by a pair of end connectors 70 and 72 whichare respectively pivotally connected near the ends of the blade as, forexample, by the pins 74 and 76 and the pins 78 and 80. The blades andthe end connectors define a quadrilateral which is variable in area andin width, as the width is measured perpendicularly from the respectiveblades. Thus, the area of the quadrilateral and the perpendicular widthbetween the blades is greater in the actuated position than in thedeactuated position. This is illustrated by comparison of FIG. 2 whichshows the switch in the deactuated position, and FIG. {which shows theswitch in the actuated position. The area in the first position, shownin FIG. 2, is less than the area of the quadrilateral in the secondposition, as shown in FIG. 4.

Means are provided for mounting the blades individually for pivotalmovement about a point intermediate the end of each blade, at least oneof the points being displaced from the respective centers of the blades.Stated differently, the pivot points for the blades must not both lie ona line bisecting the blade axes perpendicularly. One of the points maylie on the perpendicular intersecting line but if both points lie on theperpendicular bisecting line, then the switch is inoperative.

7 Both of the pivot points may lie on one side of the center of therespective blades to provide .an operative switch and mechanicalmovement. This, in certain instances, may be highly desirable. Inproviding a vibrationand shock-resistant switch, however, if itdesirable to provide a symmetrical arrangement in which the masses ofthe linkage elements are always balanced about any or all axes throughthe rotational center of the mechanism. Thus, in the preferredembodiment, the mounting means for the respective blades are so arrangedthat the blades pivot about respective points which are equallydisplaced on opposite sides of the center of the respective blades. Thisis the embodiment illustrated in FIGS. 2-5.

Referring to FIGS. 2 and 3 in particular, with comparative reference toFIGS. 4 and 5, the mounting means for the blades comprises a pair ofhubs indicated at 82 and 84 in FIG. 2. The hub 82 is illustrated inelevation in FIG. 3 and comprises a generally cylindrical body portionshown at 86, and enlarged generally cylindrical body portion shown at 88and a chamfered interconnecting portion 90 between the portions 86 and88 providing a frustoconical camriiing surface. The hub 82 also includesupper and lower annular grooves shown at 92 and 94 and is mounted forrotation in a pair of slots 96 and 98 by means of the pins 100 and 1021The slots 96 and 98 are oriented so as to extend transversely of theblade axes to permit transverse movement of the hubs upon actuation anddeactuation, as will be explained in detail. Oversize holes may besubstituted for the slots to permit transverse movement of the hubs, butmore precise action is obtainable using elongate slots having a widthapproximately' equal to the diameter of the pins 100 and 102. The blade58 may be formed integrally with the hub 82 or it may be secured theretoby a weld such as shown at 104, or any other convenient means.

The hub 84 is of like construction comprising a cylindrical portion 106,an enlarged cylindrical portion 108 joined by a chamfered portion 110forming a frustoconical camming surface and including a pair of grooves112 and 114. The hub 84 is secured in the housing by meant of the slots116 and 118 and the pins 120 and 122 in the manner described withrespect to the other hub 82.

The hubs 82 and 84 are resiliently biased toward each other by aconstraining ring 124 at the top, best illustrated in FIG. 2, and by asimilar constraining ring 126, at the bottom illustrated in FIG. 3. Uponactuation, the constraining ring 124 is resiliently deformed, as shownby a comparison of FIGS. 2 and 4. Upon deactuation, the hubs arereturned to their first, deactuated, position by the resilient forceexerted by the constraining rings 124 and 126. Equivalently, the hubsmay be biased outwardlyapart and the actuation may be accomplished bymeans for moving the hubs together against the bias force.

The switch is operated by moving the separator means in the form of anactuator cam 128 downwardly from the position shown in FIG. 3, thefirst, deactuated, position to the position shown in FIG. 5, thesecond,actuated, position. The actuator cam includes a cam-operating surfacewhich is complementary with the camming surfaces and of the hubs 82 and84 and causes the hubs 82 and 84 to move apart. The actuator cam 128 issecured to a motion-transmitting means such as a cylinder 130 which fitsover a guide pin 132 and is free to slide in reciprocal motion through acollar 134. External actuation of the switch is accomplished by pushingthe button 136, which is resiliently biased by a spring 138 in theupward position, which corresponds to the first or deactuated position.A stop 140 may, if desired, be provided in the cylinder 130 to limit themovement of the operator button 136.

The switch of this invention is conveniently arranged for beinghermetically sealed. In this configuration, the operator button 136 ismodified to include a bellows, as shown at 142 in FIG. 1, which issecured to the housing. Actuation is accomplished by compressing thebellows. In this manner, by sealing the cable entry into the housing,the entire switch can be evacuated and, if desired, backfilled with adry gas, an inert gas such as nitrogen or, for cryogenic operation,helium to prevent condensation. Once sealed, the switch is completelyunaffected by its environment.

There are a number of alternative mechanisms by which the mechanicalmovement of this invention, and the switch. can be actuated. Forexample, FIG. 6 shows an alternative embodiment of the actuatingmechanism of the invention in which the blades are carried by a pair ofhubs 144 and 146 and are constrained toward each other in contact orsubstantial contact with an idler hub 148 by means of a plurality ofconstraining devices, such as the ring 150. Actuation is accomplished byseparator means in the form of a rod 152. In FIG. 6, the mechanism isshown in the deactuated position. Upon actuation, the rod 152 is movedinwardly between the hub 146 and the idler hub 148. This causes the hub146, which is mounted by means of a pin 154 in slot 156, to moveoutwardly, to the left as shown in FIG. 6, and likewise causes the idlerhub l48,which is mounted by means of pin 162 in slot 164, and theblade-carrying hub 144, which is mounted by means of pin 158 in slot160, to move outwardly, to the right in FIG. 6. This causes equalseparation of the hubs in the respective directions and consequentactuation of the mechanism and the switch.

In FIG. 7, the idler hub is dispensed with. The blade-carrying hubs 166and 168, which may be mounted as previously described, are constrainedresiliently together by the ring 170 and are actuated by insertion ofthe rod 172 which, in a preferred embodiment, has operating surfaces 174and 176 conforming to the surfaces of the hubs. As the rod 172 is forcedbetween the hubs 166 and 168, these hubs are moved apart therebyactuating the mechanism according to the principles to be described.Actuating means of any type suitable for moving the mounting means andblade pivot points transversely for causing the blades to pivot aboutthe mounting. means may be provided equivalently. The actuatingmechanism shown in FIGS. 2 through 5 is preferred, however.

The operation of the mechanical movement, and the switch, of thisinvention is best understood by comparison of FIG. 2 with FIG. 4 andFIG. 3 with FIG. 5. The conversion of the linear movement of theactuating means, the cam 128 for example, to partial rotary, or pivotal,movement may be explained by considering the blades 58 and 60respectively, as first-order levers, with the pivot point'at one end andthe load at the other end. It will readily be seen that both ends arepivot points and loads, however, and that the direction of pivotalmovement will depend upon the relative load applied at the respectiveends of the lever.

Consider first the case wherein the separating force is exerted in theexact center of the levers in directions perpendicular to the leveraxes. In this case, the load will be applied equally at both ends ofeach lever. Since the forces are balanced, no pivotal motion will occurand the mechanism is inoperative.

Now consider the case wherein the point of application of force isdisplaced proportionally an equal distance toward the same end of therespective levers from the center, for example one-quarter the distancefrom the center to the same end of the respective levers. While theforce is applied unequally to the opposite ends of an individual lever,an equal and oppositely directed force is exerted on the same end of therespective levers by virtue of the end connector therebetween. Since theforces are equally balanced at the ends, no pivotal movement will occurand the mechanism is inoperative in this configuration.

Thus, when the point of application of force is symmetrical, i.e.,directed perpendicularly to the lever axis at proportionallycorresponding points on the respective levers, the device isinoperative. In the preferred embodiment, the levers and end connectorsform a quadrilateral which is symmetrical, i.e., a parallelogram, butthe same principles will apply even though the levers and end connectorsare asymmetrical forming a trapezoid.

Consider now the case wherein the force is applied asymmetrically. Thatis, where intermediate pivot points are located and the force is appliedat points on opposite sides of the lever centers or unequally spaced onthe same side of the lever centers, or in differing directions upon therespective levers, relative to the respective lever axes. In any ofthese situations, the forces at the ends of the levers will not bebalanced and the levers will pivot until the vectoral forces at the endscome into balance, or the pivotal movement is constrained by an externalforce such as electrical contacts.

Vibration and shock from impact of the blades, during pivotal movement,with contacts is easily prevented by positioning the contacts for beingopened and closed by the reversible pivotal movement of the blades andsuch that the blades come to rest, as a result of the balance ofvectoral forces at the ends thereof, when the respective contacts areactuated. In the preferred embodiment, the contacts, or other stopmechanisms, are positioned so as to stop the pivotal movement of theblades just slightly short of the vectoral balance point, thus placingthe contacts and the mechanism of the movement under slight butcontrolled tension during actuation. Following the principles outlinedherein, this is easily accomplished using conventional principles ofmechanical engineering.

The area of the parallelogram defined by the pivot members, blades 58and 60, and the connecting rods 70 and 72 increases upon actuationthrough a maximum, when the parallelogram is a rectangle, and thendecreases. The switch is preferably designed such that the area in thedeactuated position is smaller than the area in the actuated position,although this is not necessary to the operability of the switch.

It will be apparent from the foregoing that the blades cannot beconsidered as true first-degree levers since, first, the blades arepivoted at both ends, rather than at only one end. Secondly, the pointof application of force also constitutes the main pivot point of thelever. The mechanical movement, therefore, constitutes an application ofthe principles of both the first-order lever and the third-order lever.The movement can also be analogized to other fundamental mechanicalmovements but it is believed that the foregoing analogy is sufficientfor an understanding of the movement and the switch of this invention.

In order to provide a balancing of masses of the movement about thepivotal axes, providing mechanical stability, ease of operation, minimumfriction, and insensitivity to shock and vibration, it is desirable toprovide pivot points on opposite sides of the centers of the respectivelevers. The pivot points are preferably displaced an equal distance onthe opposite sides of the blade centers. The blades, as measured betweenthe end pivot points, are preferably of equal length and the endconnectors are also of equal length, when similarly measured.

The degree of rotation obtainable, about the pivot point of therespective blades, is a function of the relative length of the blades,the length of the end connectors, and the amount of reciprocal movementof the pivot points of the blades. For convenience, the relativedimensions and distances may be considered in terms of the length L,which is the length of the respective blades as measured from the centerpivot point thereof to the end pivot point thereof which is closest tothe center pivot point, i.e., L is the short leg of the blade. L+AL isthe long leg of the blade, or the distance from the center pivot to theend pivot furthest from the center pivot point. The length of the endconnectors may be identified as I. The minimum distance between thepivot points of the respective blades is referred to as D and themaximum distance between the center pivot points of the respectiveblades is referred to as D+AD, AD constituting the distance increasebetween the intermediate pivot points upon actuation of the mechanism.

A convenient and easily operated movement and switch can be constructedby designing the movement such that the distance AL, which is thedifference in length between the long leg and the short leg of theblade, is equal to the total movement distance between the twointermediate pivot points AD.

In a specific embodiment, AD and AL are designed to be 0.018 inch. Inobtaining this AD, the hubs and the actuator cam are chamfered on atwo-to-one slope, 0.018 inch longitudinally by 0.009 inch radially,giving a total displacement of 0.018 inch. L was designed to be 0.2l6inch and the end connector length, I, was designed to be 0. l 25 inch.

A switch constructed on these ratios provides approximately 60 totalrotation from the deactuated position, illustrated in FIG. 2, to theactuated position, illustrated in FIG. 4. Coincidentally, the torqueavailable to overcome the system friction, in inch-pounds per pound ofload, separating the pivot points is numerically approximately equal toAL. Thus, for a AL of 0.018 inch, the required torque is 0.0l8inch-pounds per pound of separating force and a AD of0.0 l 8 inchprovides 60 of linkage rotation.

One of the important features and advantages of the invention resultsfrom the use of an actuating means of the type illustrated in FIGS. 2through 5, or one of the equivalent actuating means, since the frictionin the linkage is virtually eliminated or very substantially reduced.The rotation of the hubs 82 and 84, for example, induces rotation of thecenter roller actuating cam 128. This effectively reduces friction sincethe contacting surfaces roll approximately six-sevenths of their travelwhile sliding about one-seventh. Further depression of the actuatingcam, past the 0.018-inch travel, does not affect the linkage positionand, therefore, affects any desired overtravel. Upon release of the loadon the actuator button, the actuator button is returned to its initialposition by the spring 138 and the hubs are returned to their initialposition, pivoting the blades in the reverse direction, by therestraining bias means, the resilient rings 124 and 126.

Instantaneous make and break of the contacts is easily obtainable simplyby providing an actuating cam with camoperating surfaces on the top andbottom. Thus, when the actuating cam is pushed through the pennittedtravel, the hubs are first displaced outwardly, as explained, and thenpermitted to return as the double chamfered actuating cam continuesmovement. The reverse process is obtained when the actuating cam ismoved in the opposite direction. Thus, a signal of any desiredpredetermined duration can be achieved by controlling the rate ofmovement and the length of the actuating cam.

Another embodiment of this switch is illustrated in FIGS. 8, 9, and 10,to which reference is now made. In this embodiment, the switch isenclosed in a housing 200 having a top 202,

case, as illustrated, may desirably be made of two side sections whichhave apertures-214 and 216.0n one side and apertures 218 and 220 on theother side so as to be in register. The sides are held together byhollow shafts 222 and 224 and/or by adhesive as required or by any othersuitable means. The case forms an aperture 226 and may includeinsulating plates 228 and 230 at the ends, 232 on the bottom, and 234and 236 on the respective sides.

A pair of hubs 238 and 240 are received on the shafts 22 2 and 224loosely so as to permit relative rotary and lateral gate flat elementbored at the respective ends for receiving a pivotal connecting pin, andforming a large elongate open space in the central area to accommodatethe actuating mechanism, as will be described later.

The connecting rod 250 interconnects the lower ends of the respectivesets of pivot levers by means of pivot pins 254 and 256. The form of theconnecting rod, obviously, is of little consequence in this embodimentof the invention since it is not utilized for switching. By aslight'modification thereof, however, according to the principles anddesign criteria applied to the top connecting rod, to be described, thebottom connecting rod may be used for switching as well.

The top connecting rod assembly 252 comprises a pair of elongateparallel rods 258 and 260 which are bored at the respective endsforreceiving the pivot pin connectors 262 and 264. These elongateparallel connecting rods, which form part of the connecting rod assembly252, are held in spaced relation by a pair of insulating gaskets 266 and268, an insulated s acer270' and a conductive sleeve 272 at one end,best shown in FIG. 10, and a similar construction at the other endcomprising an insulating spacer 274 and a conductive sleeve 276, shownin FIG. 8. p

This combination of pivot levers and connecting rods is resilientlyconstrained to a first deactuated position, shown in solid line, bymeans of a clip spring 278 which includes curved ends 280 and 282partially surrounding the hubs 238 and 240 and forming an aperture 284in an enlarged central portion 286 to accommodate the actuatingmechanism to be described.

The pivot mechanism is actuated by a cam 290 which includes arcuatelychamfered edges 292 and 294, best shown in phantom line in FIG. 8. Thecam 290 is actuated by means of a rod 296 which extends inreciprocalslideable relation through a sleeve 298 and a grommet 300 inaperture 226.cxternally of the housing for actuation. The rod 296 may,of course, be encased in a bellows if a gastight seal is desired. On thelower end, the cam290 is secured to a guide pin 302 which is slideablyreceived in a guide sleeve 304. The cam 290 is biased upwardly, as shownin FIG. 8, by a compression spring 306 received around the guide sleeve304 and the guidepin 302 in an annular groove 306 in the bottom of thecam 290. The compression spring 306 in combination with the restrainingleaf spring 278 resiliently bias the mechanism to a first deactuatedposition shown in solid line. Upon actuation, the cam moves downwardlycausing the hubs to move apart and the lever to pivot to the -actuatedpositiom'as shown in phantom line in FIG. I. 3

The switch is provided with two sets of resilient spring leaf contacts310 and 312 on one sideand 314 and 316 on the other side. The contact310 is secured to a connector 318 and the contact 314 is secured to aconnector 320. These connectors extend through the housing to permitexternal connection to the circuit to be actuated. The contacts 312 and316 may be a bottom 204, ends 206 and 208 and sides 210 and 212. The 1commonly connected or separately connected, as desired, in like manner,these connections not being illustrated. The connecting rod assembly andcontact arrangement can be approximately duplicated on the bottom of themechanism if desired to increase the number of switching functionspossible upon actuation.

In the deactuated position, shown in solid line in FIG. 8, an electricalcircuit is completed between contacts 314 and 316 by means of 'theconductive sleeve 272. Upon actuation, the mechanism pivots to theposition shown in phantom line in FIG. 8 and the electrical circuit iscompleted between contacts 310 and 312- by means of the conductivesleeve 276. Electrical integrity is maintained in the switch by means ofinsulating mounting blocks, as required, illustrated, for example, at322 and 324 and at 326 and 328. s

It will be apparent from the foregoing that the two embodiments of theswitch illustrated, while different in certain design characteristics,embody the same operating principles and fundamental mechanisms. Each ofthe switches comprises a pair of pivot levers which may be in the formof blades, levers, rods, etc. pivotally secured together by connectingrods. These blades or levers are mounted individually intermediate theends thereof for pivotal movement about fixed pivot points for beingrespectively displaced asymmetrically from the respective centers forthe blades. Actuating means for reciprocally moving the mounting meanstransversely of the blades or members for thereby causing the blades topivot about said mounting means are provided. Electrical contact meansare positioned for opening and closing upon the reversible pivotalmovement of the blades by the actuating means. which may be a cammovably mounted for causing relative lateral movement between the hubswhich mount the members for pivotal and lateral movement. These contactsmay be solid fixed conductive materials but are preferably in the formof leaf springs of any desired configuration. The circuit is completedby a conductive element which may be aleaf, sleeve, etc. carried on oroperated by the pivot mechanism.

The embodiments shown in the drawings are intended only to illustratevarious ways in which the switch can be constructed and notes alimitation upon the possible modesof construction. Indeed, a great manyvariations in theactual mode of. construction of the individual elementsand the combination 'as a whole are possible using design principleswell known in the art within the scope of this invention and based.

on the teachings herein.

It will bereadilyapparent from the foregoing that the movement of thisinvention has utility in numerous applications in addition to its usein'the switch of the invention. Forexample, the movement is readilyadaptable to form a shutter mechanism, simply by positioning the bladesadjacent an aperture. Furthermore, any desired amount of amplificationof linear motion into rotary motion can be achieved by providingappropriate ratios of L, L+AL, 1, Band D+AD. Mechanical advantage isalso controllable by the relative positions of the intermediate pivotpoints on the blades, either on the same side of the blade centers or onopposite sides thereof. In general, the greater the ratio of thedistance AD to the length differential AL, the greater is the movementamplification. With an 1:1 ratio of AD and AL, an increase in AD resultsin a greater angular rotation upon actuation.

The materials of construction of the hubs and actuating mechanisms areof no particular importance; however, selflubricating materials havecertain advantages. The hubs may be made of either a conductive ornonconductive material, and likewise, the actuating mechanism may bemade of either conductive or nonconductive material, regardless of thematerial of which the hubs are constructed. Nylon, phenolics,polytetrafiuoroethylene (Teflon) of the nonconductive materials andbrass, steel, aluminum and magnesium of the conductive materials aresuitable. Most other hard metals and nonmetals are also suitable for usein this application. An external lubricant may or may not be providedfor the mechanism, depending upon the environment in which the mechanismoperates and the materials of which the elements of the mechanism areconstructed. The selection of materials is well within the skill of theart.

The design of contemporary microswitches is such that they areordinarily actuated with an extremely light force. While this is animportant requirement in some applications, it is very undesirable in ahost of others. More often than not, a required activation force of apound or two is of no consequence, since tens, hundreds and frequentlythousands of pounds are available at the switch. actuator. In theseapplications, problems of vibration and shock are frequentlyencountered. Microswitches designed according to the principles setforth herein are more adaptable for operation in such environments andcan be constructed in essentially any configuration so as to be readilyinterchangeable with conventional microswitches.

Switches designed according to this invention are readily adaptable topressure sensing, temperature sensing, or for use in switching relays,wherein the activation force is provided by an electromagneticallyimpelled armature.

The inventive switch was developed particularly with the object ofsolving difi'lcult problems'experienced in aircraft and space vehicles.In these environments, absolute reliability is critical andmultiple-functioning switching circuits are frequently crucial.

A great many features of the switch can be enumerated which provideadvantages over existing microswitches. These include the wiping actionof contact surfaces for improving electrical conductivity, therebyreducing resistance loss,

. noise, and localized heating in the'switch. This switch design permitsa relatively wide separation of open contact surfaces. This feature plusthe mass balancing of the movement mechanism inhibits and essentiallyprevents accidental make or break due to shock and vibration.

Any degree of overtravel desired for a particular environment can beprovided. Any degree of pretravel can easily be provided and, ifdesired, pretravel can be virtually eliminated according to the designprinciples set forth. Friction in the mechanism is reduced to anegligible quantity by virtue of the design geometry which employsrolling action at important friction points. This leaves most of theoperating torque available for doing useful work in making and breakingthe contacts.

Loading on the operating mechanism is restricted to that force which isimposed by the ring return springs, 124 and 126, or such equivalentbiasing mechanism as is selected. Coil springs, with suitableinterconnection, for example, can be adjusted to give any desired biasforce. This prevents crushing of the case or overloading of themechanism by shock loads or overtravel of the actuating system.

The component parts of the switch are relatively simple screw machineparts which are reproducible to close tolerances. No tapped holes orscrews need be used in the switch, thereby further reducingmanufacturing costs and providing a very simple assembly procedure.

The switch has a very high degree of reliability because, for example,the contacts are wiped free of foreign matter, such as particulatesubstances or ice, upon each closing. Reliability and switch life areincreased, as compared with the conventional microswitch, by thereduction in friction, as previously noted, and further by the featureof the mechanism which prevents substantial deformation of criticalcomponents, thereby avoiding fatigue failures, Since the return biasingmeans are independent of the electrical circuitry, materials andstructures which are essentially free of metal fatigue problems areeasily obtainable.

In addition to the foregoing, the switch can be constructed in virtuallyany size and in a great many configurations to be adapted to multipleswitching systems, heavy current switching systems, and for use inenvironments requiring custom design. Modification of the switch isaccomplished simply by scaling up or down the size of the components, afeature which is not usually possible in the conventional microswitchconstruction. For example, the inventive switch has been constructedwith blades several inches long which pivot through an arc length ofseveral inches.

The switch approximates a snap-action switch, and is easily adaptable tosnap-action design, since once sufficient torque is available toovercome the initial at rest friction, then the blades pivot veryrapidly and easily to the actuated position and, similarly, deactuatevery rapidly, thereby reducing arcing during the make and break period.

As the foregoing discussion clearly indicates, a great many variationsin the dimensions and construction of the fundamental mechanism andswitch can be made based on the foregoing using the skill of the artwithout departing from the invention and the design principles set forthherein.

What is claimed is:

1. An electric switch comprising the combination of:

a pair of members pivotally secured proximate the ends thereof inrelatively spaced relation;

means mounting said members individually intermediate the ends thereoffor pivotal movement about pivot points respectively displacedasymmetrically from the respective centers of said members; actuatingmeans for reciprocally moving said mounting means transversely of themembers thereby causing said members to pivot about said mounting means;and

electrical contact means positioned for being opened and closed byreversible pivotal movement of said members by said actuating means.

2. The switch of claim I wherein the actuating means includes bias meansfor resiliently constraining the mounting means toward each other andseparator means for selectively moving the mounting means apart.

3. The switch of claim 2 wherein the members are pivotally connectedproximate the ends thereof by a pair of end connectors, the members andthe end connectors defining a quadrilateral which is variable in areaand in width upon actuation and deactuation.

4. The switch ofclaim 3 wherein the end connectors and the members areso pivotally connected as to define a parallelogram of variable area.

5. The switch of claim 4 wherein the members are mounted to pivotrespectively about pivot points displaced on opposite sides of thecenters of the respective members.

6. The switch of claim 5 wherein the pivot points are displaced equaldistances on opposite sides of the centers of the respective members.

7. The switch of claim 6 wherein the separator means displaces the pivotpoints by a distance AD, and the pivot points are displaced a distanceAL, from the respective member centers, and the distances AD and ALbeing approximately equal.

8. The switch of claim 7 wherein the constraining means comprises atleast one resilient generally annular member extending around themounting means and being so disposed as to bias the mounting meanstoward each other and to be resiliently deformed upon actuation by saidseparator means.

9. The switch of claim 8 wherein the constraining means comprises twosuch annular members so disposed as to bias the top and bottom of themounting means toward each other.

10. The switch of claim 9 wherein the electrical contact means comprisesat least one contact set which comprises at least a pair of spring leafcontacts and at least one conductor, the conductor leaf being carried ona pivot member and the spring leaf contacts being mounted so as to beresiliently displaced and wiped by the conductor leaf upon actuation ofsaid switch.

11. The switch of claim 9 wherein the electrical contact means comprisesat least one spring leaf, and at least one conductor, and conductor leafbeing carried on a pivot member and the spring leaf being mounted so asto be resiliently displaced and wiped by the conductor leafuponactuation of said switch.

12. The invention of claim ll wherein the mounting means comprises apair of spaced frustoconical cam surfaces, the

separator means comprises cam operator having a camoperating surface andmeans supporting said operator between said mounting means forreciprocal movement for moving said mounting means apart upon reciprocalmovement of said operating surface upon said cam surfaces.

13. Theinvention of claim 11 wherein the separator means (comprises anidler hub mounted between said mounting means and substantially incontact therewithand an operator rod mounted for being inserted betweenone of said mounting means and said idler hub, said m'o'unting meansbeing moved apart through contact with said operator rod and movement ofsion as to move said hubs apart.

l Theinvention of claim 2 wherein the separator means comprises an idlerhub mounted between said mounting means and substantially in contacttherewith and an operator rod mounted for being inserted between one ofsaid mounting means and said idler hub, said mounting means being movedapart through contact with said operator rod and movement of said idlerspindle.

16. The invention of claim 2 wherein said mounting means comprise hubsmounted proximate each other and .said separator means comprises anoperator rod mounted for movement between said hubs, said rod being ofsuch dimension as to move said hubs apart.

17. The invention of claim 2 wherein the mounting means comprises a pairof spaced frustoconical cam surfaces, the separator means comprises acam operator having a camoperating surface and means supporting saidoperator between said mounting means for reciprocal movement for movingsaid mounting means apart upon reciprocal movement of said operatingsurface upon said cam surface.

18. The switch of claim 17 wherein the members are pivotally connectedproximate the ends thereof by a pair of end connectors, the members andend connectors defining a parallelogram which is variable in area and inwidth upon ac? tuation and deactuation.

19. The switch of claim 18 wherein the members are mounted to pivotrespectively about pivot points displaced a distance AL on oppositesides of the respective member centers.

20. The switch of claim 19 wherein the mounting means are displaced adistance AD upon actuation and wherein AD is approximately equal to AL.

21. The switch of claim 17 wherein the members are mounted to pivotrespectively about pivot points displaced a distance AL on oppositesides. of the respective member 'centers.

22. The switch of claim 21 wherein the mounting means are displaced adistance AD upon actuation and wherein AD is approximately equal to AL.

23. The switch of claim 2 wherein the electrical contact means comprisesat least one contact at which comprises at least a pair of spring leafcontacts and at least one conductor, the conductor being carried on apivot member and the spring leaf contacts being mounted so as to beresiliently displaced and wiped by the conductor upon actuation of saidswitch.

24. The switch of claim 2 wherein the members are mounted to pivotrespectively about pivot points displaced a distance AL on oppositesides of the respective member centers. i

25. The switch of claim 24 wherein the mounting means are displaced adistance AD upon actuation and wherein AD is approximately equal to AL.

26. An electrical switch comprising:

a switch housing;

a pair of blades;

end connectors pivotally interconnecting the respective ends of theblades to define a variable area parallelogram;

means mounting the blades in the housing for pivotal motion aboutrespective pivot points and transverse notion of the pivot points of therespective blades;

means biasing the pivot pointsin a first direction;

actuating means operable from without the housing forselectivelyreciprocally moving the pivot points relative to each othertransversely of the blades, the coaction of the pivotal mounting meansand pivotal interconnection of the blade ends causing said blades topivot when the pivot points are so moved; and

contact means in the housing operable by the blades for opening andclosing at least one circuit upon pivotal motion of said blades.

27. The switch of claim 26 wherein the mounting means comprises a pairof spaced hubs having cam surfaces thereon and the actuator comprises acam operator supported for reciprocal movement between the hubs, saidoperator having a cam-operating surface adapted to coact with the camsurfaces on the hubs for moving said hubs apart in a second directionagainst the force exerted by the biasing means, the pivotal motion ofsaid blades causing the cam operating surface and the cam surfaces to bein substantially rolling contact.

28. Theswitch of claim 27 wherein. the blades are mounted to pivotrespectively about pivot points displaced a distance AL on oppositesidesof the respective blade centers.

29. The switch of claim 28 wherein the mounting means are displaced adistance AD upon actuation and wherein AD is approximately equal to AL.

30. The switch of claim 26 wherein the contact means comprises at leastone contact set which comprises at least a pair of spring leaf contactsand at least one conductor, the conductor being carried on a blade andthe spring leaf contacts being mounted so as to be resiliently displacedand wiped by the conductor leaf upon actuation of said switch.

31. The switch of claim 30 wherein the mounting means comprises apair ofspaced hubs having cam surfaces thereon and the actuator comprises a camoperator supported for reciprocal movement between the hubs, saidoperator having a cam-operating surface adapted to coact-with the camsurfaces on the hubs for moving said hubs apart in a second directionagainst the force exerted by the biasing means. the pivotal motion. ofsaid blades causing the cam-operating sur face and the cam surfaces tobe in substantially rolling contact.

32. The switch of claim 31 wherein the blades are mounted to pivotrespectively about pivot points displaced a distance AL on oppositesides of the respective blade centers.

33. The switch of claim 32 wherein the mounting means are displaced adistance AD upon actuation and wherein AD is approximately equal to AL.

34. As a mechanical movement for converting reciprocal motion to rotarymotion, the combination comprising:

a pair of elongate substantially rigid members;

end connectors pivotally interconnecting the respective ends ofsaidmembers to define a variable-area quadrilateral;

means mounting the members for pivotal motion about respective pivotpoints and transverse motion of the pivot points of the respectivemembers;

means biasing the pivot points in a first direction;

actuating means for selectively reciprocally moving the pivot pointsrelative to each other transversely of the members, coaction of thepivotal mounting means and pivotal interconnection of the member endscausing said members to pivot when the pivot points are so moved.

35. The movement of claim 34 wherein the mounting means comprises a pairof spaced hubs having cam surfaces thereon and the actuator comprises acam operator supported for reciprocal movement between the hubs,saidoperator having a cam-operating surface adapted to coact with thecam surfaces on the hubs for moving said hubs apart in a seconddirection against'the force exerted by the biasing means, the

pivotal motion of said members causing the cam operating surface and thecam surfaces to be in substantially rolling contact 36. The movement ofclaim 35 wherein the members are mounted to pivot respectively aboutpivot points displaced a distance AL on opposite sides of the respectiveblade center.

37. The movement of claim 36 wherein the mounting means are displaced adistance AD upon actuation and wherein AD is approximately equal to AL.

38. A switch comprising the combination of:

a housing;

a pair of shafts supported in the housing;

a hub received loosely on each shaft for rotary and lateral movement;

at least one pivot lever supported by each hub;

a pair of connecting rods pivotally secured respectively to the ends ofthe pivot levers to form a quadrilateral; resilient means biasing thehubs toward each other;

means operable from without the housing for displacing the hubslaterally from each other for actuating the switch; and

means in the housing for making and/or breaking at least one electricalconnection, including movable means associated with the pivot levers,constructed and disposed for being operated upon relative lateralmovement of the hubs, such lateral movement resulting in pivotalmovement of the pivot levers and generally longitudinal reciprocalmovement of the connecting rods.

39. The switch of claim 38 wherein:

at least a pair of spaced pivot levers are supported on each hub;

the means for displacing the hubs comprises a cam movable along an axisperpendicular to the axes of the hubs; and

the means for making and/or breaking electrical connection includes atleast one set of electrical contacts and conductive means movable by thepivot levers for closing and opening an electrical circuit between saidcontacts.

i i I! i 8

1. An electric switch comprising the combination of: a pair of memberspivotally secured proximate the ends thereof in relatively spacedrelation; means mounting said members individually intermediate the endsthereof for pivotal movement about pivot points respectively displacedasymmetrically from the respective centers of said members; actuatingmeans for reciprocally moving said mounting means transversely of themembers thereby causing said members to pivot about said mounting means;and electrical contact means positioned for being opened and closed byreversible pivotal movement of said members by said actuating means. 2.The switch of claim 1 wherein the actuating means includes bias meansfor resiliently constraining the mounting means toward each other andseparator means for selectively moving the mounting means apart.
 3. Theswitch of claim 2 wherein the members are pivotally connected proximatethe ends thereof by a pair of end connectors, the members and the endconnectors defining a quadrilateral which is variable in area and inwidth upon actuation and deactuation.
 4. The switch of claim 3 whereinthe end connectors and the members are so pivotally connected as todefine a parallelogram of variable area.
 5. The switch of claim 4wherein the members are mounted to pivot respectively about pivot pointsdisplaced on opposite sides of the centers of the respective members. 6.The switch of claim 5 wherein the pivot points are displaced equaldistances on opposite sides of the centers of the respective members. 7.The switch of claim 6 wherein the separator means displaces the pivotpoints by a distance Delta D, and the pivot points are displaced adistance Delta L, from the respective member centers, and the distancesDelta D and Delta L being approximately equal.
 8. The switch of claim 7wherein the constraining means comprises at least one resilientgenerally annular member extending around the mounting means and beingso disposed as to bias the mounting means toward each other and to beresiliently deformed upon actuation by said separator means.
 9. Theswitch of claim 8 wherein the constraining means comprises two suchannular members so disposed as to bias the top and bottom of themounting means toward each other.
 10. The switch of claim 9 wherein theelectrical contact means comprises at least one contact set whichcomprises at least a pair of spring leaf contacts and at least oneconductor, the conductor leaf being carried on a pivot member and thespring leaf contacts being mounted so as to be resiliently displaced andwiped by the conductor leaf upon actuation of said switch.
 11. Theswitch of claim 9 wherein the electrical contact means comprises atleast one spring leaf, and at least one conductor, and conductor leafbeing carried on a pivot member and the spring leaf being mounted so asto be resiliently displaced and wiped by the conductor leaf uponactuation of said switch.
 12. The invention of claim 11 wherein themounting means comprises a pair of spaced frustoconical cam surfaces,the separator means comprises cam operator having a cam-operatingsurface and means supporting said operator between said mounting meansfor reciprocal movement for moving said mounting means apart uponreciprocal movement of said operating surface upon said cam surfaces.13. The invention of claim 11 wherein the separator means comprises anidler hub mounted between said mounting means and substantially incontact therewith and an operator rod mounted for being inserted betweenone of said mounting means and said idler hub, said mounting means beingmoved apart through contact with said operator rod and movement of saididler spindle.
 14. The invention of claim 1 wherein said mounting meanscomprise hubs mounted proximate each other and said separator meanscomprises an operator rod mounted for movement between said hubs, saidrod being of such dimension as to move said hubs apart.
 15. Theinvention of claim 2 wherein the separator means comprises an idler hubmounted between said mounting means and substantially in contacttherewith and an operator rod mounted for being inserted between one ofsaid mounting means and said idler hub, said mounting means being movedapart through contact with said operator rod and movement of said idlerspindle.
 16. The invention of claim 2 wherein said mounting meanscomprise hubs mounted proximate each other and said separator meanscomprises an operator rod mounted for movement between said hubs, saidrod being of such dimension as to move said hubs apart.
 17. Theinvention of claim 2 wherein the mounting means comprises a pair ofspaced frustoconical cam surfaces, the separator means comprises a camoperator having a cam-operating surface and means supporting saidoperator between said mounting means for reciprocal movement for movingsaid mounting means apart upon reciprocal movement of said operatingsurface upon said cam surface.
 18. The switch of claim 17 wherein themembers are pivotally connected proximate the ends thereof by a pair ofend connectors, the members and end connectors defining a parallelogramwhich is variable in area and in width upon actuation and deactuation.19. The switch of claim 18 wherein the members are mounted to pivotrespectively about pivot points displaced a distance Delta L on oppositesides of the respective member centers.
 20. The switch of claim 19wherein the mounting means are displaced a distance Delta D uponactuation and wherein Delta D is approximately equal to Delta L.
 21. Theswitch of claim 17 wherein the members are mounted to pivot respectivelyabout pivot points displaced a distance Delta L on opposite sides of therespective member centers.
 22. The switch of claim 21 wherein themounting means are displaced a distance Delta D upon actuation andwherein Delta D is approximately equal to Delta L.
 23. The switch ofclaim 2 wherein the electrical contact means comprises at least onecontact at which comprises at least a pair of spring leaf contacts andat least one conductor, the conductor being carried on a pivot memberand the spring leaf contacts being mounted so as to be resilientlydisplaced and wiped by the conductor upon actuation of said switch. 24.The switch of claim 2 wherein the members are mounted to pivotrespectively about pivot points displaced a distance Delta L on oppositesides of the respective member centers.
 25. The switch of claim 24wherein the mounting means are displaced a distance Delta D uponactuation and wherein Delta D is approximately equal to Delta L.
 26. Anelectrical switch comprising: a switch housing; a pair of blades; endconnectors pivotally interconnecting the respective ends of the bladesto define a variable area parallelogram; means mounting the blades inthe housing for pivotal motion about respective pivot points andtransverse notion of the pivot points of the respective blades; meaNsbiasing the pivot points in a first direction; actuating means operablefrom without the housing for selectively reciprocally moving the pivotpoints relative to each other transversely of the blades, the coactionof the pivotal mounting means and pivotal interconnection of the bladeends causing said blades to pivot when the pivot points are so moved;and contact means in the housing operable by the blades for opening andclosing at least one circuit upon pivotal motion of said blades.
 27. Theswitch of claim 26 wherein the mounting means comprises a pair of spacedhubs having cam surfaces thereon and the actuator comprises a camoperator supported for reciprocal movement between the hubs, saidoperator having a cam-operating surface adapted to coact with the camsurfaces on the hubs for moving said hubs apart in a second directionagainst the force exerted by the biasing means, the pivotal motion ofsaid blades causing the cam operating surface and the cam surfaces to bein substantially rolling contact.
 28. The switch of claim 27 wherein theblades are mounted to pivot respectively about pivot points displaced adistance Delta L on opposite sides of the respective blade centers. 29.The switch of claim 28 wherein the mounting means are displaced adistance Delta D upon actuation and wherein Delta D is approximatelyequal to Delta L.
 30. The switch of claim 26 wherein the contact meanscomprises at least one contact set which comprises at least a pair ofspring leaf contacts and at least one conductor, the conductor beingcarried on a blade and the spring leaf contacts being mounted so as tobe resiliently displaced and wiped by the conductor leaf upon actuationof said switch.
 31. The switch of claim 30 wherein the mounting meanscomprises a pair of spaced hubs having cam surfaces thereon and theactuator comprises a cam operator supported for reciprocal movementbetween the hubs, said operator having a cam-operating surface adaptedto coact with the cam surfaces on the hubs for moving said hubs apart ina second direction against the force exerted by the biasing means, thepivotal motion of said blades causing the cam-operating surface and thecam surfaces to be in substantially rolling contact.
 32. The switch ofclaim 31 wherein the blades are mounted to pivot respectively aboutpivot points displaced a distance Delta L on opposite sides of therespective blade centers.
 33. The switch of claim 32 wherein themounting means are displaced a distance Delta D upon actuation andwherein Delta D is approximately equal to Delta L.
 34. As a mechanicalmovement for converting reciprocal motion to rotary motion, thecombination comprising: a pair of elongate substantially rigid members;end connectors pivotally interconnecting the respective ends of saidmembers to define a variable-area quadrilateral; means mounting themembers for pivotal motion about respective pivot points and transversemotion of the pivot points of the respective members; means biasing thepivot points in a first direction; actuating means for selectivelyreciprocally moving the pivot points relative to each other transverselyof the members, coaction of the pivotal mounting means and pivotalinterconnection of the member ends causing said members to pivot whenthe pivot points are so moved.
 35. The movement of claim 34 wherein themounting means comprises a pair of spaced hubs having cam surfacesthereon and the actuator comprises a cam operator supported forreciprocal movement between the hubs, said operator having acam-operating surface adapted to coact with the cam surfaces on the hubsfor moving said hubs apart in a second direction against the forceexerted by the biasing means, the pivotal motion of said members causingthe cam operating surface and the cam surfaces to be in substantiallyrolling contact.
 36. The movement of claim 35 wherein the members aremounted to pivot respectively about pivot points displaced a distAnceDelta L on opposite sides of the respective blade center.
 37. Themovement of claim 36 wherein the mounting means are displaced a distanceDelta D upon actuation and wherein Delta D is approximately equal toDelta L.
 38. A switch comprising the combination of: a housing; a pairof shafts supported in the housing; a hub received loosely on each shaftfor rotary and lateral movement; at least one pivot lever supported byeach hub; a pair of connecting rods pivotally secured respectively tothe ends of the pivot levers to form a quadrilateral; resilient meansbiasing the hubs toward each other; means operable from without thehousing for displacing the hubs laterally from each other for actuatingthe switch; and means in the housing for making and/or breaking at leastone electrical connection, including movable means associated with thepivot levers, constructed and disposed for being operated upon relativelateral movement of the hubs, such lateral movement resulting in pivotalmovement of the pivot levers and generally longitudinal reciprocalmovement of the connecting rods.
 39. The switch of claim 38 wherein: atleast a pair of spaced pivot levers are supported on each hub; the meansfor displacing the hubs comprises a cam movable along an axisperpendicular to the axes of the hubs; and the means for making and/orbreaking electrical connection includes at least one set of electricalcontacts and conductive means movable by the pivot levers for closingand opening an electrical circuit between said contacts.